Herbicidal Effects of Picloram on Bermudagrass

Abstract

The herbicide 4-amino-3,5,6-trichloropicolinic acid (picloram) was applied to several bermudagrasses (Cynodon spp.). Most of the grasses were susceptible to picloram; however, some were resistant and recovered within 16 months from the initial treatment. There were no detectable metabolites of 14C picloram in bermudagrass (C. dactylon (L.) Pers. ‘U-3’) or common Kentucky bluegrass (Poa pratensis L.). Also, there were no abnormal changes in cells of swollen nodes of picloram-treated bermudagrass that could explain the selective herbicidal injury of picloram on bermudagrass.